Topical Foam for Simultaneous Treatment and Decontamination of Chemical Warfare Agents on Dermal Exposure

Abstract

Being highly toxic and a quick-acting vesicant, even small amounts of lewisite if not decontaminated immediately are rapidly absorbed into systemic circulation via skin exposure, leading to acute poisoning and death. The skin is the first major target to such chemical weapons. Although the stratum corneum provides a barrier lewisite being a lipophilic molecule that readily permeates this barrier. This necessitates, making early and thorough decontamination prior to manifestation of adverse effects. For this, we aimed to decontaminate skin using an antidote-loaded topical foam, followed by treating local and systemic toxicity using the same formulation. Successful incorporation of 1% antidote into a decontaminating topical foam and the delivery of 1.78 ± 0.21 µg/sq cm into dermatomed porcine ear skin within five minutes of application was achieved. Decontamination after five minutes of exposure (88.43%), as well as prolonged exposure (94.53%; 3 h) to methyl salicylate, a warfare chemical simulant, was demonstrated. The developed formulation demonstrated the potential to back-extract simulant from skin tissue but could not purge simulant penetrated systemic circulation. However, systemic delivery of the antidote was demonstrated, establishing the potential to treat the toxicity caused by the remnant warfare chemicals.

Keywords: Foaming; Formulation; In vitro permeation testing; Microemulsion; Transdermal drug delivery.